With rapid development of a packet service and an intelligent terminal, a service of a high speed and a large data volume has an increasing demand for a spectrum. A centimeter wave frequency band generally refers to a spectrum ranging from 3 GHz to 30 GHz, and a millimeter wave frequency band generally refers to a spectrum ranging from 30 GHz to 300 GHz, which may be collectively referred to as a millimeter wave. Because of a large amount of available bandwidth, the millimeter wave will be a potential target spectrum in future development of 5G communications and 3rd Generation Partnership Project (3GPP) Long Term Evolution Advanced (LTE-A). In the prior art, cellular communications such as Long Term Evolution (LTE) usually uses a frequency band of approximately 2 GHz or lower, and an LTE-A small cell enhancement standardization project is studying and using a 3.5 GHz frequency band. In the Institute of Electrical and Electronics Engineers (IEEE) 802.11ad standard, a 60 GHz frequency band is used for a wireless local area network (WLAN), and is usually used for indoor communication at a short distance of approximately 10 meters.
A 6 GHz or higher frequency band has not been used in cellular communication in the prior art. A main challenge of using a millimeter-wave high frequency band in cellular communication lies in that relatively large free-space attenuation exists in this band; in addition, attenuation caused by absorption and scattering by air, rain, fog, buildings or other objects is extremely severe. A beamforming technology is considered as a potential technology that can compensate a severe millimeter-wave pathloss, and a massive multiple-input multiple-output (Massive MIMO or Large Scale MIMO) system is considered as a potential direction for implementing the beamforming technology in a millimeter wave frequency band.
The IEEE 802.11ad standard supports beamforming. A process of performing beam training between two nodes in communication is as follows: A node 1 separately sends training beacons in multiple different directions in a beam manner, and a node 2 receives the training beacons in a quasi-omni manner and identifies a best beam a; the node 2 separately sends beacons in multiple different directions in a beam manner, and the node 1 receives the beacons in a quasi-omni manner and identifies a best beam b; and the node 2 reports the best beam a to the node 1, and the node 1 reports the best beam b to the node 2, so as to find an optimal matched beam pair. Subsequently, data communication is performed in directions of the beam pair. However, the 802.11ad is usually used in short-distance indoor point-to-point communication, in which a beam training process is complex, a delay is relatively long, and efficiency is relatively low, and cannot be directly applied to a cellular mobile communications system.
Current cellular communication is performed in a low frequency band, and an omni transmission manner is generally used for a common signal in a cell, such as a synchronization channel and a broadcast channel. If the omni transmission manner is still used for a common signal in a millimeter-wave high-frequency-band cellular communications system, a transmission range of the common signal is limited, for example, is several dozens of meters, and this results in an adverse effect on power consumption of a base station, coverage and a capacity of a cell, and the like.